What you need to know about early onset colon cancer

Cases of early onset colorectal cancer, occurring in people between the ages of 20 and 45, have increased in recent decades. However, the reason for the uptick in cases is not well understood. Dr. Benjamin Musher, medical director of medical oncology at the Dan L Duncan Comprehensive Cancer Center, explains the potential causes and risk factors. 

“Although some early onset cancers are caused by genetic factors, the majority of people under the age of 50 who are diagnosed with colorectal cancer do not have an identifiable genetic cause,” said Musher, professor of medicine and holder of the Barry Stephen Smith Memorial Endowed Professorship at Baylor College of Medicine. “We are not sure what’s behind the rising incidence of young-onset colorectal cancer, but we believe environmental factors are largely responsible.”

General risk factors for colon cancer include obesity, inflammatory bowel disease, a prior history of colon polyps and/or cancer, family history of colon cancer, a known predisposing germline mutation, alcohol, smoking and the “western diet” (diet high in processed foods, refined grains, red meat and low in fruits and vegetables). “Unfortunately, none of these factors fully explain the rising rates of colorectal cancer in younger people,” Musher said.

“Emerging data point to changes in the gut microbiome, the bacteria that live in the bowel, as a potential cause of early-onset colon cancer,” he said. “Studies have shown bacterial content in the bowel is different in people with colon cancer compared to the general population.”

There are steps that everyone can take to lower their general risk for colon cancer:

• Eat a healthy diet with plenty of fiber
• Minimize red meat consumption and eat more fish and plant-based proteins
• Limit sugary drinks and alcohol consumption
• Maintain a healthy weight
• Do not smoke
• Follow preventive screening guidelines

Current guidelines state that people who have an average risk for colon cancer should start screening at age 45. Musher recommends that people with certain risk factors or conditions start screening earlier:

• Family history of colon cancer or polyps
• Inflammatory bowel disease such as Crohn’s disease or ulcerative colitis
• Known genetic syndrome predisposing to colorectal cancer

Certain symptoms, such as rectal bleeding and changes in stool habits, may warrant diagnostic testing. “Rectal bleeding in young individuals may often be attributed to hemorrhoids, but persistent bleeding with or without changes in stool habits should be taken seriously and discussed with your primary care physician or gastroenterologist,” he said.

Musher stresses that adherence to screening guidelines is imperative to prevent cancer. While the incidence of colorectal cancer has been rising among younger people, rates of colon cancer have fallen in people over age 50 due to colorectal cancer screening, which can prevent cancer by detecting and removing precancerous polyps before malignant transformation.